Making intervertebral disc prostheses comprising two vertebral elements or “plates”, intended to be anchored to the respective vertebrae and an intermediate damping core placed between both of these plates, is known. The prosthesis may be of the type with a dual articular movement, i.e. having both of its plates jointed relatively to the intermediate core; in this case, the intermediate core comprises two shells forming two articular surfaces for cooperating with conjugate articular surfaces possessed by the plates, and a flexible element placed between both of these shells. The prosthesis may also be of the type with a simple articular movement, i.e. having a single one of these two plates jointed relatively to the intermediate core; in this case, the intermediate core is formed by a shell or by a flexible element placed between this shell and the non-jointed plate, the flexible element fixedly received by this non-jointed plate.
The existing intervertebral disc prostheses of either one of these two types, do not give perfect satisfaction. Notably, they do not always perfectly reproduce the damping characteristics exhibited by natural vertebral discs. Further, the repeated movements which they undergo, result in more or less rapid wear of the flexible damping elements, which wear leads to an alteration of the articular movement.
When the intermediate core is mobile relatively to both plates, there moreover exists a notable risk of this core being expelled.
Further, the existing prostheses may be relatively complex to assemble.
The publication of patent application No. US 2009/192617 A1 describes an intervertebral disc prosthesis including two plates intended to be anchored to the respective vertebrae, and an intermediate damping core placed between both of these plates, this intermediate core comprising a first shell forming an articular surface for cooperating with a conjugate articular surface possessed by a first plate, and a flexible element placed between this first shell and a part for receiving this core, said first shell and said first receiving part comprising means for guiding their mutual movement for bringing them closer or moving them away from each other, made possible by the flexibility of said flexible element.